Design of a Single-Stage Dual Active Bridge Microinverter With Wide Load Adaptability Based on Loss Optimization

This article presents an optimized design of a single-stage dual active bridge (DAB) dc–ac converter with off-grid load capability. DAB converters have attracted attention due to their bidirectional power transmission and high power density characteristics. However, adaptability to loads is required during off-grid operation of energy storage devices. Based on the linearization of control variables, a new control loop is established in this article. The objective is to minimize current stress and root mean square current, which constrains the outer phase-shift angle, thereby enhancing system efficiency. Furthermore, from the perspective of the loss model, the optimal operating frequency range of the system was studied based on the selected switching devices. Combined with winding methods, the parameters of the magnetic components were optimized. This further improved the system's efficiency. A 600 W DAB microinverter prototype was built and experimentally verified on various loads. The results confirmed that the proposed method can improve the overall system efficiency and achieve a peak efficiency of 97.89% under resistive load.